Synchronous rectifier and controller for inductive coupling

Abstract

A synchronous rectifier is arranged to rectify inductively coupled power using PETs (field effect transistors) to minimize the voltage drop of the rectifier, which minimizes power loss. Power loss is an important consideration in applications where fairly significant power is coupled to a device (such as a battery charger or other energy storage device) for a fairly short time (such as less than one hour) at a fairly low voltage (such as around 2.5 to 4.5 volts). Body diodes of the PETs can be used to supply power for bootstrapping and control logic for controlling the PFTs.

1 . A synchronous switch circuit, comprising:
 an inductor for producing an alternating current voltage in response to a received changing electromagnetic field;   a synchronous rectifier comprising a first and second high side switch and a first and second low side switch that rectify the alternating current voltage to produce a direct current voltage;   an energy storage device for storing energy from the direct current voltage; and   control circuitry for controlling the first and second high side switch and a first and second low side switch in response to a state of the alternating current voltage signal.   
     
     
         2 .- 20 . (canceled)